1. Field of the Invention
The present invention relates to a sheet feeding apparatus for an image forming device, and more particularly to a sheet feeding apparatus which includes a sheet feeding cassette removably connected to an image forming device main body and a pickup roller to pick up a sheet.
2. Description of the Related Art
An image forming device transfers a print medium such as paper or a thin plastic plate (hereinafter, referred to as a ‘sheet’) and prints images or characters on the transferred sheet. Exemplary image forming devices include a printer and a copier. A general image forming device has a sheet feeding apparatus to continuously feed sheets to an image forming device main body for consecutive printing.
In order to serve the aforementioned purpose, a variety of sheet feeding apparatuses have been suggested for the image forming device. In general, a sheet feeding apparatus including a sheet feeding cassette and a pickup roller have been used.
The general sheet feeding apparatus has the sheet feeding cassette removably installed in the image forming device main body, and the pickup roller installed in the image forming device main body is positioned above the sheet feeding cassette mounted on the image forming device main body.
Referring to FIG. 1, the sheet feeding cassette 10 includes a cassette frame 12, a sheet pressure plate 16 and a compression coil spring 18. The cassette frame 12 guides the sheet feeding cassette 10 to be mounted in or removed from the image forming device main body. A handle hole 15 is formed on the front surface 14 of the cassette frame 12 for mounting or removing the sheet feeding cassette 10.
The sheet pressure plate 16 is positioned on the cassette frame 12, and has one end hinge-connected to a support bracket 13 protruded from the bottom of the cassette frame 12. The other end of the sheet pressure plate 16 is elastically supported by the compression coil spring 18. Accordingly, the sheet pressure plate 16 is upwardly slanted to the bottom surface of the cassette frame 12.
The operation of the above-described sheet feeding apparatus will now be explained.
The sheets are loaded on the sheet pressure plate 16. The user pushes the sheet feeding cassette 10 into the image forming device main body by holding the handle hole 15 of the front surface 14 of the cassette frame 12. When the sheet feeding cassette 10 is mounted on the image forming device main body, the top sheet loaded on the sheet pressure plate 16 contacts the pickup roller. Here, the sheet pressure plate 16 is elastically supported upward by the compression coil spring 18, and thus pressure is applied to the top sheet by the pickup roller. Accordingly, when the pickup roller is rotated, the top sheet is transferred to the image forming device main body due to a frictional force between the pickup roller and the sheet.
However, the sheet feeding apparatus using the sheet feeding cassette has a disadvantage in that the sheet can be jammed between the sheet feeding cassette and the pickup roller depending on the type of sheet or due to abrasion of the pickup roller. When the sheet is jammed, the sheets loaded on the sheet feeding cassette 10 cannot be fed. It is thus necessary to remove the jammed sheet. In this case, the sheet feeding cassette 10 must be separated from the image forming device main body to pull the jammed sheet out of the pickup roller.
In the sheet feeding apparatus using the sheet feeding cassette 10, the sheet feeding cassette 10 is separated so as to remove the jammed sheet. However, since the sheet pressure plate 16 pressures the sheet against the pickup roller, the jammed sheet is damaged due to a force of pulling the sheet feeding cassette 10. That is, when the sheet feeding cassette 10 is separated in order to remove the jammed sheet, the non-used sheet is torn, which increases consumption of sheets and reduces reliability of the image forming device.